(1) When impurities adhere to the surface of the ingot or the composition of the ingot segregates, there is a large amount of segregation floating debris on the surface of the ingot. The ingot has not been homogenized or the homogenization effect is not good. There is a certain amount of hard metal particles in the ingot. During the extrusion process, when the metal flows through the working strip, the segregation floating debris or hard metal particles attach to the surface of the working strip or cause damage to the working strip, ultimately scratching the surface of the profile;
(2) There are debris in the mold cavity or work strip, and the hardness of the mold work strip is low. When squeezed, it will damage the surface of the work strip and scratch the profile;
(3) There are hard inclusions in the exposed metal or graphite rods on the unloading track or bed, which can scratch the surface of the profile when in contact with it;
(4) When the fork rod sends the profile from the unloading track to the swinging bed, the profile is scratched due to excessive speed;